Automatic temperature control for furnaces



1933- G. STEVENSON AUTOMATIC TEMPERATURE CONTROL FOR FURNACES Filed May 16, 1932 2 Sheets-Sheet l 15, 1933- G. STEVENSON AUTOMATIC TEMPERATURE CONTROL FOR FURNACES 2 Sheets-Sheet 2 Filed May 16, 932.

Zinnamor;

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Patented Aug. 15, 1933 UN E TA one-half to Claude Ind.

A. Hoover, Richmond,

Application May 16,1932. Serial $16,511,613f) .3 Claims. '(c ass-104p The object of this invention, broadly stated, is the provision of a mechanism to be employed in connection with heating furnaces, and more particularly ,those of the hot-air type, whereby the fuel therein will be caused to burn with such uniformity that the heat transmitted therefrom will be maintained at the predetermined degree of temperature desired.

.Further, my object is-the provision of a mechanism, of the nature set forth, which may be employed with various makes -of furnaces, will be practically automatic in its operation, which will eventuate in the saving of fuel, prolonging the life of the furnace, providing a more health: ful atmosphere in the rooms heated thereby, and which can be manufactured, sold, and installed, at a comparatively low price V y Other minor objects and particular advantages of my invention will suggest themselves in the course of the following description,- and that which'is new will be corelated in the appended claims,

The-preferred means for carrying out the principles of my inventionin a practical and a mechanically eflicient manner, is shown in the accompanying two sheets of drawings, in which Figure 1 shows a side elevation of a heating fur- 'nace, showing the jacket as partly broken away in order to show theupper portion ofv the furnace proper, and showing, in section} parts of the building in which the furnace is supposed to be located. Figure 2 is a front elevation of the same, but without any part of the furnace broken" away.

Figure 3 is an enlarged detail front view of the control arms, as detached from the furnace, and showing other parts of my mechanism attached thereto in their normal positions. Figure 4 is the same as Fig. 3, except that it is taken-at right angles thereto, that is, looking directly downwardly thereupon. Figure 5 is'a front'elevation of the auxiliary or manual control arm. Figure 6 is a perspective view of a portion of, themain control arm, and the adjustable weight which.

iscarried thereby. Figure '7 is a side elevation of -the thermo-arm alone; and Figure 8 is a top'plan view of the same; Figure 9 is a cross section of the thermo-arm, as taken on the line 9 -9 of Fig. '7'

I Referring now to the-drawings in detail: letter,

:A designates the lower'fioor linegon which the furnace-restsyand letter B denotes the-upper floor line, above which is the space to be heated.

like, partsithroughe EJ "PATENT ornce Y Letter C denotes the furnace drum or. shell,

that is, the body of the furnace,'and its upper end. is closed by the dome C.

Located rearwardly from the upper portion of the body C is the radiator D, theupper portion of which is-interiorly connected with the member C; The'connection betweenthe members C and D comprises the corresponding flanged collars E and F, each of which is integral with its respective member 0 and D. Said collars are connected by a plurality of bolts-G. Letter J denotes the furnace jacket; which incloses the body C and the radiator D, and is spaced therefrom, and j its top covers the dome C, but located some distance thereabove; Extending back from the interior of the'radi'ator D,'and extending through the jacket'J; is

the collar K, which connects with the vent or smoke' pipe L.' 1 Covering an'opening therefor in the front of the body, C, and aborre'spon'ding,opening in the jacket J, is the front-assembly which includesthe frame with the fuel door N and the ash-pit door O mounted thereto, and adapted to close '80 their respective openings. Mounted overf an aperture in the door Q is the'front draft damper P, having a finger P extending horizontally'to. the left therefrom. 5

' The pipe L is provided with achecli- 'draft ape'rture therein,' which is adapted to, be closed by the hinged damperR'. i f

The parts which are "predominantly parts of my invention, comprise the balance-bar 1, which is adapted to be operated calorically, as will hereinafter'be fully explained. Said bar is provided 'with enlarged endsl and"1,- front and rear respectively, each having a vertical eye'formed "therethroughinto which extend the j upper-ffthreaded end portions of the connecting-rods. 2 and 3;" respe'ctively, where each is 'adjustably' se; cured by nuts4 and 5, respectively. Formed in"- t'egral with the lower face of the bard isJthe V-shaped fulcrum 6; having a sharp lower edge 6'; whiehflis formed crescent-shaped whereby it fits the curvature'of the surface of the dome C',

as shown'in Fig. 1. The. fulcrumo'is located somewhat nearer to'the rear end of the barl, in order that the forward end of said bar 1;.will have 1 a greater vertical movement thanif it'were placed in the'eenter of the-bar 1, but thispositioneventuates in the fulcrum being located rearwardly of' the center ofthe dome C, as shown. The rear end 'of' the bar'l is anchored by means of-the rod 3, whose lower' end is'attached to one of the "bolts G, while the-up'per'en'd of the rod-3 is vided with an aperture 9.

' 17, through which operates the chain 18.

adjustably attached to the rear end 1" of the bar 1, by means of the nut 5.

Numeral 7 denotes the balance-bar, which has a relatively large aperture '7 formed therethrough in the center thereof. Numeral 9 denotes the-manual control arm, which is formed oifset, with the inner end portion thereof adapted to contact with the face of the bar Z, while its outer portion is spaced from said bar but it may be parallel therewith, as shown.

Integral with, or rigidly attached, with the inner face of the inner portion of the'arm 9, is a disc 8 which fits rotatably in the aperture '7. Said disc 8 has a bolt aperture 8' formed eccen trically therethrough and it registers with a like aperture formed through the inner portion of the arm 9 and an aperture in the center of the upper edge of the frame M, to receive the bolt 10, whereby the arm 9 will be eccentrically left of the center of the arm 7, and they may be used selectively for the purpose of adjustment. Numeral 12 designates a weight, which is adjustably secured on the left-hand portion of the arm 7, by means of the thumb-nut 13.

Numeral 14 designates the manually operable -thermal' control, affording means whereby a certain degree 'of control may be imparted to the furnace by a person located at a distance therefrom, that is, in a room located above the furnace, whereby said control may be set in order that a predetermined degree of temperature may be maintained until the heating element is near exhaustion, or at any desired time thereafter. .Extending down from the member 14, through the floor B, is a chain 15, whose lower end is pro- Secured to any suitable permanent member'above the "furnace, as the joists b and b, are the respective pulleys 16 and The rear end of said chain 18 is secured to the damper R, from which it extends through the pulleys 17 and 18, and then downwardly through the pulley 19, with its lower end indirectly attached to the finger P of the damper P, that is to say, it is secured in the eye of the-outwardly extending bolt 21. Also said chain 18 is secured 'intermediately of the pulley 16 and the finger P, to the outer or right-hand end portion of the bar 7, by means of a the bolt 20.

I It is to be understood that while the particular kindef metalof which the furnace ismade is immaterial, yet my invention will be more effective and positive if the furnace body C be, made of steel, for the sole reason that steel is much more P will beopen. Desiring now to operate the furnace the control member 14 should first be turned such as will turn the arm 9 upwardly, whereby the saideccentric will lift, the righthand end of the bar 7, thereby causing the lower portion of the chain 18 to slightly open the damper P, and at the same time closing the damper R.

A fire may now be started, or renewed, in the furnace, and as the damper P is open, and the damper R is closed, the fire will increase in intensity, thereby expanding the body C, which will eventuate in lifting the bar 1, and as it is anchored at its rear end, therefore the front end thereof will be raised, and its movements compounded both by reason of the rear end being anchored and by reason of the location of the fulcrum 6. The upward movement of the oar 1 will, by reason of the connecting rod 2, eventuate in lifting the bar 7, thereby partly opening the damper P and closing the damper B. As the furnace heats up the expansion of the metal body C will' cause the member 1 of the bar 1 to move gradually upward, at which time the chain 15 should be fully released by turning the member 1 1.

Now, as the furnace arrives at the temperature such as to provide the desired warmth to the space being heated, it is evident that the left hand end portion of the bar '7 willbe raised, thereby lowering the right-hand end of the bar '7, which will, at the proper time, ciosethe damper and open the damper B. These movements of the bar '7, actuated by the expansion and the contraction of the body C, intensified by the movements of the for-ward end of the bar 1, will manifestly operate the dampers? and R such as to automatically maintain a uniform tern erature. And it is also to be observed that the degreeof temperature to be maintained thereby may be manually changed as desired, by means of the thermal control 14. 7

In order to adapt the device to various conditions, in relation to the installation thereof, the weight 12 may be adjusted at any point desired along the left-hand portion of the bar 7, by which proper balance may be given to themechanism. V

The weight 11 is provided simplyforassuring that the arm .9 will turn downwardly when the chain 15 is slackenedthereby causing thead- ,justment to be more quick and positive. 7

It is to be observed that the eccentric disc 8, and its relation with the operation 'of the arm 9, affords means for raising and lowering the chain 18, and therefore operating the dampers P and R, independently of the normal thermal actuation 7 applied to the bar 7.

- It is to be understood that the forward end of the bar 1 extends through a vertical 'slot 22,

which is formed through the jacket J; said. slot being always closed by means of the plate 23, which is secured around the bar land moves up and down therewith, in sliding contact with the I jacket J, whereby said slot is always closed.

It is to be understood that various changes may be made in the details of construction and operation, from that herein shown and described, without departing from the spirit of my invention or sacrificing any of the advantages thereof which are new and useful,

Havin now fullshown and described the best exemplification of my invention; to me known at this time, what I claim and desire to secure by Letters Patent of the United States, is-

1. In combination with a heatingfurnace having 'a jacket inclosure and provided with a vent pipe in the rear and having a draft damper in said pipe and with a check damperlocated in the front; an automatic temperature control comr, prising a thermo-bar extending across above the top of the furnace and within said jacket, a sharp edged fulcrum which is 'crescenteshaped longitudinally and formed integral with the under side of said bar and located in the rear of the center thereof with said edge resting on the top of shown and described.

2. In combination with a hot air furnace inclosed by a jacket spaced therefrom and dampers located at the front and the rear thereof; a temperature control comprising a thermo-bar extending across above the top of the furnace andwithin the space formed by the jacketand the furnace, a fulcrum formed onthe lower edge of said bar and located in the rear of the center thereof with its edge resting on top of the fur-' nace, means for rigidly anchoring the rearendz of said ,bar to the upper portion of the furnace whereby the front only may be raised and lowered by thermal action of said bar,a balance-bar ex-f' tending across the front'of the jacket and having a comparatively large aperture formed through its center, a disc rotatably -mounted in said aperture with an eccentric aperture formed therein, an offset manual control arm pivoted at its inner end in said aperture in said disc, a weight permanently attached to the offset portion of the manual control arm, means for pivotedly connecting both the balance arm and the control arm to the jacket of the furnace, a

chain having its lower end attached to the outer free end of the manual control arm with the upper end of said chain attached to a thermal control device, a second chain attached to the outer end of the balance-bar and extending upward and downwardly; therefrom and having each of'its ends attached to a separate damper, a rod pivoted to'the thermal-bar with its lower end pivoted .tolthe balance-barat a point remote from the center of the balance-bar, and a weight adjustably mounted on the balance-bar, both said weight and said rod connection with the-balance-bar being on that portion thereof beyond the center remote from said chainssubstantially as shown. 7

3. In combination with a heating furnace inclosed by a jacket and provided with front and reardampers and a thermo-contr-ol device located at a distance therefrom, a thermobar supported on the top of the, furnace and inclosed by said jacket, means for .anch oring the rear end of said bar, with its forward end projecting through an aperture in the'jacket, a suspension rod extending downwardly from the projecting end of said bar, a balance bar extending across the front of said jacket and suspended by the center of said balance-bar, a manual control arm pivoted at'its inner end of said disc, a chain attached. to the outer end of said manual control. arm with .its upper end attached to a manually operable thermal control device, and means for adjusting the operations of said balance bar, all substantially as shown and described.

GEORGE STEVENSON. I

said rod, a damper-chain attached to one end of said'balance-bar and extending both upwardly and downwardly therefrom with each of its ends attached to a different damper, an eccentric disc rotatably mounted in an aperture formed'in 

